A number of different torch nozzles have been developed in the art for attachment to portable pressurized gas fuel cylinders, canisters or containers of liquified petroleum products such as propane. These types of gas torches are frequently used by plumbers, electricians and mechanics in soldering, brazing and welding operations.
In many of these applications the character of the flame produced by the torch is of critical importance to the effective, efficient or even successful completion of the particular job. For example, when binding together two or more fusible materials by melting, a particular flame temperature must be reached and maintained. Fluctuations of the shape of the fame or in the flame temperature produced by the torch during the melting operation could needlessly prolong the job or prevent the binding from being properly completed.
Such fluctuations can be caused by a number of factors. Specifically, as the torch is used, gas is depleted from the cylinder and the internal pressure of the cylinder decreases. Without proper regulation this leads to the production of a smaller flame at an insufficient temperature for the particular operation being conducted. Further, it should be appreciated that changes in the ambient temperature can also effect the internal pressure of the cylinder and, therefore, the pressure with which gas is emitted from the cylinder.
For example, a plumber may spend the morning operating a torch outdoors in freezing temperatures. During this time the plumber adjusts the characteristics of the torch to suit the particular application to which the torch is being used. Later in the day outdoor temperature may rise or his work may move indoors to a heated area. As the ambient temperature of the fuel gas cylinder rises, so does the pressure of the fuel gas in the cylinder.
Pressurized fuel gas subsequently emitted from the cylinder is, therefore, at a constantly rising pressure requiring continuous adjustment. The operator of the torch has no alternative but to be constantly alert to change the setting as the gas warms.
This prior art practice of constant adjustment has proven to be a satisfactory arrangement over the years. However, it is obviously desirable to avoid this cumbersome and inconvenient practice of having to continually change the valve setting, if possible. Previously, avoidance of this difficulty has been attempted by providing in a torch nozzle assembly a mechanism to automatically regulate the gas fuel delivery pressure. Some of these attempts have been reasonably effective in producing a flame of reasonably constant characteristics under a wide range of operating conditions.
Examples of the various regulator mechanisms utilized to date are provided from a review of U.S. Pat. Nos. 3,736,093 to Bowman et al. and 4,348,172 to Miller. The Bowman patent discloses a nozzle assembly including a regulator valve having a spring and diaphragm combination. This regulator valve automatically increases and decreases the fuel flow from a fuel gas tank or cylinder in response to a decrease or increase, respectively, in the internal tank pressure caused by the ambient operating temperature.
The Miller patent also discloses a regulator valve for maintaining a substantially constant gas pressure. The regulator valve includes a valve core, a regulator piston and a cooperating "spider like" contact plate. During operation the gas pressure serves to lift the piston from the plate against the pressure of a spring so as to allow the passage of gas.
While the spring and diaphragm approach in Bowman and the valve core, regulator piston and contact plate combination in Miller are relatively effective in regulating the pressure of gas delivery, they are not without their disadvantages. These relatively complicated mechanisms are expensive to manufacture, difficult to adjust accurately and time consuming and costly to maintain in proper working order. As such, a need is identified for an improved gas pressure regulator mechanism that provides effective performance while being both simple and inexpensive to construct and maintain.